The "Hidden Immunity Idol" is a special item in the reality TV show Survivor. Contestants can find this idol hidden in various locations on the island. If a player possesses the idol, they can use it to protect themselves from being voted out during a tribal council. To use the idol, a contestant must play it before the votes are revealed. If they do, any votes cast against them are negated, allowing them to stay in the game. The idol adds an element of strategy, as players must decide when to reveal their possession of it and how to use it effectively.